Multiple Node.js Applications on Oracle Always Free Cloud

What if you want to host multiple Oracle JET applications? You can do it easily on Oracle Always Free Cloud. The solution is described in the below diagram:

You should wrap Oracle JET application into Node.js and deploy it to Oracle Compute Instance through Docker container. This is described in my previous post - Running Oracle JET in Oracle Cloud Free Tier.

Make sure to create Docker container with a port different than 80. To host multiple Oracle JET apps, you will need to create multiple containers, each assigned with a unique port. For example, I'm using port 5000:

docker run -p 5000:3000 -d --name appname dockeruser/dockerimage

This will map standard Node port 3000 to port 5000, accessible internally within Oracle Compute Instance. We can direct external traffic from port 80 to port 5000 (or any other port, mapped with Docker container) through Nginx.

Install Nginx:

yum install nginx

Go to Nginx folder:

cd etc/nginx

Edit configuration file:

nano nginx.conf

Add context root configuration for Oracle JET application, to be directed to local port 5000:

location /invoicingdemoui/ {
     proxy_pass http://127.0.0.1:5000/;
}

To allow HTTP call from Nginx to port 5000 (or other port), run this command (more about it on Stackoverflow):

setsebool -P httpd_can_network_connect 1

Reload Nginx:

systemctl reload nginx

Check Nginx status:

systemctl status nginx

That's all. Your Oracle JET app (demo URL) now accessible from the outside:

Getting Your Hands Dirty with TensorFlow 2.0 and Keras API

Diving into technical details of the regression model creation with TensorFlow 2.0 and Keras API. In TensorFlow 2.0, Keras comes out of the box with TensorFlow library. API is simplified and more convenient to use.

Read the complete article here.

SEO for Single Page Oracle (SPA) JET Application

This is a quick tip post related to Oracle JET.

SEO (search engine optimization) is a must for a public website or public-facing app. Search engines do indexing well for static HTML pages. Oracle JET on contrary follows SPA (single page application) approach with dynamic UI. This makes it harder for the search engines to build an index for such an app. The same applies to any other SPA implementations with Angular, React, Vue.js, etc.

If you want to build SEO support for Oracle JET, similar solutions as for Angular, React or Vue.js SPAs apps can be applied.

One of the simpler and reliable solutions - generate static HTML pages for Oracle JET SPA app. You can follow this article, it explains how the same can be done for Angular - SEO for Single Page Applications.

Machine Learning with SQL

Python (and soon JavaScript with TensorFlow.js) is a dominant language for Machine Learning. What about SQL? There is a way to build/run Machine Learning models in SQL. There could be a benefit to run model training close to the database, where data stays. With SQL we can leverage strong data analysis out of the box and run algorithms without fetching data to the outside world (which could be an expensive operation in terms of performance, especially with large datasets). This post is to describe how to do Machine Learning in the database with SQL.

Read more in my Towards Data Science post.

Running Oracle JET in Oracle Cloud Free Tier

OOW'19 stands up from recent years OOW conferences with important announcement - Oracle Cloud Free Tier offering. This offering includes two free DB instances and two free compute VM instances. What else you could wish for the side and hobby projects? This is a strong move by Oracle and it should boost Oracle Cloud. Read more about it in Oracle Cloud Free Tier page.

It was interesting to test how to deploy Oracle JET app to Oracle Always Free instance of compute VM. I will not go through the initial steps, related how to create VM instance and enable internet access (for the port 80). You can read all that in a nice write up from Dimitri Gielis post.

Assuming you already have created Oracle JET app and want to deploy it. One way would be to set up Node.js and Nginx on the compute VM and pull app source code from Git. I prefer another way - to go through Docker container, Nginx would act as HTTP server to redirect requests to Docker container port. But in this post for simplicity reasons, we are not going to look into Nginx setup - will focus only on JET deployment through Docker container.

1. Create an empty Node application (follow these steps):

express --view=pug

2. Add dependencies, go into the Node app and run:

npm install

3. Copy Oracle JET content from web folder into Node app public folder (remove existing files)

4. Inside Node app, adjust app.js file, comment out these lines:

var usersRouter = require('./routes/users');

app.set('view engine', 'pug');

app.use('/users', usersRouter);

5. Keep only index.js file in router folder

6. Remove template files from views folder

7. Update index.js file to redirect to Oracle JET index.html

router.get('/', function(req, res, next) {
  //res.render('index', { title: 'Express' });
  res.sendFile('index.html', {root: './public/'});
});

8. Note down port 3000 info from bin/www, this is the port Node app will run in Docker container

9. Create Dockerfile inside Node app folder (follow these steps). Content:

FROM node:10

# Create app directory
WORKDIR /usr/src/app

# Install app dependencies
# A wildcard is used to ensure both package.json AND package-lock.json are copied
# where available (npm@5+)
COPY package*.json ./

RUN npm install
# If you are building your code for production
# RUN npm ci --only=production

# Bundle app source
COPY . .

EXPOSE 3000
CMD [ "node", "./bin/www" ]

10. Create .dockerignore file. Content:

node_modules
npm-debug.log

11. Build Docker image locally, by running below command inside Node app:

docker build -t username/imagename -f ./Dockerfile .

12. Push Docker container to Docker Hub. This way we will be able to pull container from Oracle compute VM in the cloud:

docker push username/imagename

---

Next steps are executed inside Oracle compute VM. You should connect through SSH to run below commands.

13. Install Docker (run sudo su):

yum install docker-engine

14. Enable Docker:

systemctl enable docker

15. Start Docker:

systemctl start docker

16. Check Docker status:

systemctl status docker.service

17. Check Docker version:

docker version

18. Login into Docker Hub, to be able to pull the container with Node app. If login doesn't work (access permission issue), run this command: sudo usermod -a -G docker $USER

docker login

19. Run container:

docker run -p 80:3000 -d --name appname username/imagename

Node app with Oracle JET content can be accessed by port 80 using public IP of your Oracle container VM: http://130.61.241.30/index.html

Oracle JET app runs on Oracle container VM free tier:

Comprehensive TensorFlow.js Example

I have implemented an app which includes TensorFlow.js API usage. First I will walk you through the app functionality and then will dive into implementation details. This app implements a business report execution time prediction use case (this time in JavaScript), which was explained in my previous post — Report Time Execution Prediction with Keras and TensorFlow.

Read more in my Towards Data Science post.

Using Web Worker for Long Tasks in Oracle JET

JavaScript app runs in a single thread. This means if there is a long-running resource-intensive operation - the thread will be blocked and the page will stay frozen until operation completes. Obviously, this is not user-friendly and such behavior should be avoided. We can use Web Workers, through Web Workers we could run long-running operations in separate threads, without blocking the main thread. Code running in Web Worker doesn't have access to UI DOM, this means logic coded in Web Worker should operate with logic which is not directly related to UI.

Sample app contains commented code in dashboard.js. This code blocks main thread for 10 seconds, if you uncomment it - you will see that app becomes frozen for 10 seconds:

Web Worker is defined in dashboard.js. Web Worker is a separate JS file, which is being used for Worker object. API allows to send and receive messages, this way we can communicate to and from Web Worker (start a new task and receive message when task is completed):

Web Worker code - onmessage invoked when the message arrives from the main thread. postMessage sends message back to the main thread:

The sample app is available on GitHub repo.